\DOC is_const

\TYPE {is_const : term -> bool}

\SYNOPSIS
Tests a term to see if it is a constant.

\DESCRIBE
If {c} is an instance of a previously declared HOL constant, then
{is_const c} returns {true}; otherwise the result is {false}.

\FAILURE
Never fails.

\SEEALSO
Term.mk_const, Term.dest_const, Term.is_var, Term.is_comb, Term.is_abs.
\ENDDOC