The way you define f is a Python function, not a symbolic expression. In particular, the name of the input does not matter. So, there is no point to deal with f(y) which requires that y is defined (as a symbol).
What you can do is the following:
sage: plot(f,(0,1))
Launched png viewer for Graphics object consisting of 1 graphics primitive
Asked: 2015-07-09 11:34:34 +0200
Seen: 1,719 times
Last updated: Jul 09 '15
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