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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 hacking_docstring_start_space(physical_line, previous_logical, tokens):
 r"""Check for docstring not starting with space. OpenStack HACKING guide recommendation for docstring: Docstring should not start with space Okay: def foo():
\n '''This is good.''' Okay: def foo():
\n r'''This is good.''' Okay: def foo():
\n a = ''' This is not a docstring.''' Okay: def foo():
\n pass\n ''' This is not.''' H401: def foo():
\n ''' This is not.''' H401: def foo():
\n r''' This is not.''' """

    docstring = is_docstring(tokens, previous_logical)
    if docstring:
        start, start_triple = _find_first_of(docstring, START_DOCSTRING_TRIPLE)
        if docstring[len(start_triple)] == ' ':
            # docstrings get tokenized on the last line of the docstring, so
            # we don't know the exact position.
            return (0, "H401: docstring should not start with"
                    " a space")