def read_input(in_file, header=True):
    """Read and return all GO terms that are found in an open file.

    Parameters
    ----------
    in_file : an open file object
    header : bool, optional
        If the file contains a header that should be stripped

    Returns
    -------
    A list with all GO-term id's that are present in the given file.

    """
    if header:
        next(in_file)
    return [line.rstrip() for line in in_file]