This is documentation for Mathematica 8, which was
based on an earlier version of the Wolfram Language.
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Identity

Identity[expr]
gives expr (the identity operation).
Plot a collection of functions together with the line:
Identity is removed from functional composition:
The first derivative of the identity is the constant 1:
Sequence acts as a general identity for several arguments:
Identity as a pure function:
Tabulate square roots of values without using auxiliary variables:
New in 1