SYM_CONV : conv
STRUCTURE
SYNOPSIS
Interchanges the left and right-hand sides of an equation.
DESCRIPTION
When applied to an equational term t1 = t2, the conversion SYM_CONV returns the theorem:
   |- (t1 = t2) = (t2 = t1)

FAILURE
Fails if applied to a term that is not an equation.
SEEALSO
HOL  Kananaskis-14