atom_length/2 ISOatom_length(+Atom, -Length)
Length is the number of characters of the atom Atom.
atom, must be nonvar
integer
instantiation_errorAtom is uninstantiated
type_errorAtom is not an atom, or Length cannot be unified with an integer
domain_errorLength < 0
atom_length/2, atom_concat/3, sub_atom/5.