def assign_coordinate_file_ending(program: str):
    """
    Returns the coordinate file ending specific to the program

    Paramaeters
    -----------
    program: str
        Program being used.

    Returns
    -------
    file_ending: str
        string of the file ending
    """
    if program == 'Tinker':
        return '.xyz'
    elif program == 'Test':
        return '.npy'
    elif program == 'CP2K':
        return '.pdb'
    elif program == 'QE':
        return '.pw'