# FunctionSpaceAssertions(R, F)¶

constant(x) tells the pattern matcher that x should match only the symbol 'x and no other quantity. Error: if x is not a symbol.
multiple(x) tells the pattern matcher that x should preferably match a multi-term quantity in a sum or product. For matching on lists, multiple(x) tells the pattern matcher that x should match a list instead of an element of a list. Error: if x is not a symbol.
optional(x) tells the pattern matcher that x can match an identity (0 in a sum, 1 in a product or exponentiation). Error: if x is not a symbol.