Stop guessing :)
http://search.cpan.org/src/PETDANCE/WWW-Mechanize-1.34/Changes

1.21_03     Sat Oct  7 01:21:46 CDT 2006
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[THINGS THAT MAY BREAK YOUR CODE]
*   The methods $mech->form() and $mech->follow() have been removed.
    They've been deprecated since 1.10, which was released in Feb 2005
+.
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