symbol s provides the symbol s, even if s currently has a value.
i1 : num
o1 = num
o1 : Symbol
i2 : num = 5
o2 = 5
i3 : num
o3 = 5
i4 : symbol num
o4 = num
o4 : Symbol
If s is an operator, then the corresponding symbol is provided. This symbol is used by the interpreter in constructing keys for methods associated to the symbol.