\DOC is_imp_only

\TYPE {is_imp_only : term -> bool}

\SYNOPSIS
Tests a term to see if it is an implication.

\DESCRIBE
If {M} has the form {t1 ==> t2} then {is_imp_only M} returns {true}.
If the term is not an implication, the result is {false}.

\FAILURE
Never fails.

\SEEALSO
boolSyntax.is_imp, boolSyntax.mk_imp, boolSyntax.dest_imp, boolSyntax.dest_imp_only, boolSyntax.list_mk_imp, boolSyntax.strip_imp.
\ENDDOC