Option variable
incharDefault value: %i
inchar is the prefix of the labels of expressions entered by the user.
Maxima automatically constructs a label for each input expression
by concatenating inchar and linenum.
inchar may be assigned any string or symbol, not necessarily a single character.
(%i1) inchar: "input"; (%o1) input (input1) expand ((a+b)^3); 3 2 2 3 (%o1) b + 3 a b + 3 a b + a (input2)