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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def datetime_parsing(text, base_date=datetime.now()):
 """ Extract datetime objects from a string of text. """

    matches = []
    found_array = []

    # Find the position in the string
    for expression, function in regex:
        for match in expression.finditer(text):
            matches.append((match.group(), function(match, base_date), match.span()))

    # Wrap the matched text with TAG element to prevent nested selections
    for match, value, spans in matches:
        subn = re.subn(
            '(?!<TAG[^>]*?>)' + match + '(?![^<]*?</TAG>)', '<TAG>' + match + '</TAG>', text
        )
        text = subn[0]
        is_substituted = subn[1]
        if is_substituted != 0:
            found_array.append((match, value, spans))

    # To preserve order of the match, sort based on the start position
    return sorted(found_array, key=lambda match: match and match[2][0])