Issue a MongoDB command.

        Send command `command` to the database and return the
        response. If `command` is an instance of :class:`basestring`
        (:class:`str` in python 3) then the command {`command`: `value`}
        will be sent. Otherwise, `command` must be an instance of
        :class:`dict` and will be sent as is.

        Any additional keyword arguments will be added to the final
        command document before it is sent.

        For example, a command like ``{buildinfo: 1}`` can be sent
        using:

        >>> db.command("buildinfo")

        For a command where the value matters, like ``{collstats:
        collection_name}`` we can do:

        >>> db.command("collstats", collection_name)

        For commands that take additional arguments we can use
        kwargs. So ``{filemd5: object_id, root: file_root}`` becomes:

        >>> db.command("filemd5", object_id, root=file_root)

        :Parameters:
          - `command`: document representing the command to be issued,
            or the name of the command (for simple commands only).

            .. note:: the order of keys in the `command` document is
               significant (the "verb" must come first), so commands
               which require multiple keys (e.g. `findandmodify`)
               should use an instance of :class:`~bson.son.SON` or
               a string and kwargs instead of a Python `dict`.

          - `value` (optional): value to use for the command verb when
            `command` is passed as a string
          - `check` (optional): check the response for errors, raising
            :class:`~pymongo.errors.OperationFailure` if there are any
          - `allowable_errors`: if `check` is ``True``, error messages
            in this list will be ignored by error-checking
          - `read_preference`: The read preference for this operation.
            See :mod:`~pymongo.read_preferences` for options.
          - `codec_options`: A :class:`~bson.codec_options.CodecOptions`
            instance.
          - `**kwargs` (optional): additional keyword arguments will
            be added to the command document before it is sent

        .. note:: :meth:`command` does **not** obey :attr:`read_preference`
           or :attr:`codec_options`. You must use the `read_preference` and
           `codec_options` parameters instead.

        .. versionchanged:: 3.0
           Removed the `as_class`, `fields`, `uuid_subtype`, `tag_sets`,
           and `secondary_acceptable_latency_ms` option.
           Removed `compile_re` option: PyMongo now always represents BSON
           regular expressions as :class:`~bson.regex.Regex` objects. Use
           :meth:`~bson.regex.Regex.try_compile` to attempt to convert from a
           BSON regular expression to a Python regular expression object.
           Added the `codec_options` parameter.

        .. versionchanged:: 2.7
           Added `compile_re` option. If set to False, PyMongo represented BSON
           regular expressions as :class:`~bson.regex.Regex` objects instead of
           attempting to compile BSON regular expressions as Python native
           regular expressions, thus preventing errors for some incompatible
           patterns, see `PYTHON-500`_.

        .. versionchanged:: 2.3
           Added `tag_sets` and `secondary_acceptable_latency_ms` options.
        .. versionchanged:: 2.2
           Added support for `as_class` - the class you want to use for
           the resulting documents

        .. _PYTHON-500: https://jira.mongodb.org/browse/PYTHON-500

        .. mongodoc:: commands

def command(self, command, value=1, check=True,
                allowable_errors=None, read_preference=ReadPreference.PRIMARY,
                codec_options=DEFAULT_CODEC_OPTIONS, **kwargs):
        """Issue a MongoDB command.

        Send command `command` to the database and return the
        response. If `command` is an instance of :class:`basestring`
        (:class:`str` in python 3) then the command {`command`: `value`}
        will be sent. Otherwise, `command` must be an instance of
        :class:`dict` and will be sent as is.

        Any additional keyword arguments will be added to the final
        command document before it is sent.

        For example, a command like ``{buildinfo: 1}`` can be sent
        using:

        >>> db.command("buildinfo")

        For a command where the value matters, like ``{collstats:
        collection_name}`` we can do:

        >>> db.command("collstats", collection_name)

        For commands that take additional arguments we can use
        kwargs. So ``{filemd5: object_id, root: file_root}`` becomes:

        >>> db.command("filemd5", object_id, root=file_root)

        :Parameters:
          - `command`: document representing the command to be issued,
            or the name of the command (for simple commands only).

            .. note:: the order of keys in the `command` document is
               significant (the "verb" must come first), so commands
               which require multiple keys (e.g. `findandmodify`)
               should use an instance of :class:`~bson.son.SON` or
               a string and kwargs instead of a Python `dict`.

          - `value` (optional): value to use for the command verb when
            `command` is passed as a string
          - `check` (optional): check the response for errors, raising
            :class:`~pymongo.errors.OperationFailure` if there are any
          - `allowable_errors`: if `check` is ``True``, error messages
            in this list will be ignored by error-checking
          - `read_preference`: The read preference for this operation.
            See :mod:`~pymongo.read_preferences` for options.
          - `codec_options`: A :class:`~bson.codec_options.CodecOptions`
            instance.
          - `**kwargs` (optional): additional keyword arguments will
            be added to the command document before it is sent

        .. note:: :meth:`command` does **not** obey :attr:`read_preference`
           or :attr:`codec_options`. You must use the `read_preference` and
           `codec_options` parameters instead.

        .. versionchanged:: 3.0
           Removed the `as_class`, `fields`, `uuid_subtype`, `tag_sets`,
           and `secondary_acceptable_latency_ms` option.
           Removed `compile_re` option: PyMongo now always represents BSON
           regular expressions as :class:`~bson.regex.Regex` objects. Use
           :meth:`~bson.regex.Regex.try_compile` to attempt to convert from a
           BSON regular expression to a Python regular expression object.
           Added the `codec_options` parameter.

        .. versionchanged:: 2.7
           Added `compile_re` option. If set to False, PyMongo represented BSON
           regular expressions as :class:`~bson.regex.Regex` objects instead of
           attempting to compile BSON regular expressions as Python native
           regular expressions, thus preventing errors for some incompatible
           patterns, see `PYTHON-500`_.

        .. versionchanged:: 2.3
           Added `tag_sets` and `secondary_acceptable_latency_ms` options.
        .. versionchanged:: 2.2
           Added support for `as_class` - the class you want to use for
           the resulting documents

        .. _PYTHON-500: https://jira.mongodb.org/browse/PYTHON-500

        .. mongodoc:: commands
        """
        client = self.__client
        with client._socket_for_reads(read_preference) as (sock_info, slave_ok):
            return self._command(sock_info, command, slave_ok, value,
                                 check, allowable_errors, read_preference,
                                 codec_options, **kwargs)