human
Complete this python program:
def _indent(text, prefix, predicate=None):
assistant
#Here is the Python program you requested.

    """Adds \prefix\ to the beginning of selected lines in \text\.
    If \predicate\ is provided, \prefix\ will only be added to the lines
    where \predicate(line)\ is True. If \predicate\ is not provided,
    it will default to adding \prefix\ to all non-empty lines that do not
    consist solely of whitespace characters.
    """
    if (predicate is None):
        predicate = (lambda line: line.strip())
    def prefixed_lines():
        for line in text.splitlines(True):
            (yield ((prefix + line) if predicate(line) else line))
    return ''.join(prefixed_lines())