def METHOD_NAME(type_count):
    """
    If the underlying records are ONLY of type `integer`, `number`,
    or `date-time`, then return that datatype.
    If the underlying records are of type `integer` and `number` only,
    return `number`.
    Otherwise return `string`.
    """
    to_return = 'string'
    if type_count.get('date-time', 0) > 0:
        return 'date-time'
    if len(type_count) == 1:
        if type_count.get('integer', 0) > 0:
            to_return = 'integer'
        elif type_count.get('number', 0) > 0:
            to_return = 'number'
    elif (len(type_count) == 2 and type_count.get('integer', 0) > 0 and type_count.get('number', 0) > 0): # noqa
        to_return = 'number'
    return to_return