def pick_type(types):
    """ if there is only one type found
    in a column, then use that. if multiple
    types are found, default back to string.
    """
    type_set = set(types)
    if len(type_set) == 1:
        return list(type_set)[0]
    elif set(['IntType', 'FloatType']) == type_set:
        return 'FloatType'
    else:
        return 'StringType'
