You can prevent an expression from being evaluated by quoting it, either by preceding it with ’ or with the quote or hold) command.
If a is a variable, then a:=quote(a) (or a:=hold(a)) is equivalent to purge(a) (for the sake of Maple compatibility). It returns the value of this variable (or the hypothesis done on this variable).
a:=2;quote(2+3*a) |
or:
a:=2;'2+3*a' |
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