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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _pack(formatstring, value):
 """Pack a value into a bytestring. Uses the built-in :mod:`struct` Python module. Args: * formatstring (str):
 String for the packing. See the :mod:`struct` module for details. * value (depends on formatstring):
 The value to be packed Returns: A bytestring (str). Raises: ValueError Note that the :mod:`struct` module produces byte buffers for Python3, but bytestrings for Python2. This is compensated for automatically. """

    _checkString(formatstring, description='formatstring', minlength=1)

    try:
        result = struct.pack(formatstring, value)
    except:
        errortext = 'The value to send is probably out of range, as the num-to-bytestring conversion failed.'
        errortext += ' Value: {0!r} Struct format code is: {1}'
        raise ValueError(errortext.format(value, formatstring))

    if sys.version_info[0] > 2:
        return str(result, encoding='latin1')  # Convert types to make it Python3 compatible
    return result