<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def preprocess(msg_body, delimiter, content_type='text/plain'):
 """Prepares msg_body for being stripped. Replaces link brackets so that they couldn't be taken for quotation marker. Splits line in two if splitter pattern preceded by some text on the same line (done only for 'On <date> <person> wrote:' pattern). Converts msg_body into a unicode. """

    msg_body = _replace_link_brackets(msg_body)

    msg_body = _wrap_splitter_with_newline(msg_body, delimiter, content_type)

    return msg_body