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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 is_python_command(line):
 """ Given an input, checks whether the input is a request for python or notself. This can be a version, a python runtime name, or a generic 'python' or 'pythonX.Y' :param str line: A potential request to find python :returns: Whether the line is a python lookup :rtype: bool """


    if not isinstance(line, six.string_types):
        raise TypeError("Not a valid command to check: {0!r}".format(line))

    from pipenv.vendor.pythonfinder.utils import PYTHON_IMPLEMENTATIONS
    is_version = re.match(r'[\d\.]+', line)
    if (line.startswith("python") or is_version or
            any(line.startswith(v) for v in PYTHON_IMPLEMENTATIONS)):
        return True
    # we are less sure about this but we can guess
    if line.startswith("py"):
        return True
    return False