<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def text_concat(*args, **kwargs):
 """ Concatenate several values as a text string with an optional separator """

    separator = text_value(kwargs.get("separator", ""))
    values = filter(None, [text_value(v) for v in args])
    return separator.join(values)