import ast


def parse_comment(comment):
    """
    Parse a comment of the form
    # investigation_time=50.0, imt="PGA", ...
    and returns it as pairs of strings:

    >>> parse_comment('''path=('b1',), time=50.0, imt="PGA"''')
    [('path', ('b1',)), ('time', 50.0), ('imt', 'PGA')]
    """
    names, vals = [], []
    pieces = comment.split('=')
    for i, piece in enumerate(pieces):
        if i == 0:  # first line
            names.append(piece.strip())
        elif i == len(pieces) - 1:  # last line
            vals.append(ast.literal_eval(piece))
        else:
            val, name = piece.rsplit(',', 1)
            vals.append(ast.literal_eval(val))
            names.append(name.strip())
    return list(zip(names, vals))