\DOC ALL_CONV

\TYPE {ALL_CONV : conv}

\SYNOPSIS
Conversion that always succeeds and leaves a term unchanged.

\KEYWORDS
conversion, identity.

\DESCRIBE
When applied to a term {`t`}, the conversion {ALL_CONV} returns the
theorem {|- t = t}. It is just {REFL} explicitly regarded as a conversion.

\FAILURE
Never fails.

\USES
Identity element for {THENC}.

\SEEALSO
NO_CONV, REFL.

\ENDDOC