def remove_extension(file_name):

    """

    Remove 3 letters and 4 letters extension from filename

    >>> remove_extension('my file.tex')

    'my file'

    >>> remove_extension('my file.html')

    'my file'

    >>> remove_extension('my file')

    'my file'

    """

    for point_loc in [3,4]:

        if len(file_name)>point_loc and file_name[-point_loc-1] == '.':

            return file_name[:-point_loc-1] 

    return file_name

if __name__ == "__main__":

    import doctest

    doctest.testmod()