(self)
Test whether the formula is a literal.

        A literal is a positive or negative Boolean symbol.
Test whether the formula is a literal.
Test whether the formula is a literal .
def is_literal(self):
        """Test whether the formula is a literal.

        A literal is a positive or negative Boolean symbol.
        """
        if self.is_symbol(BOOL):
            return True
        if self.is_not():
            return self.arg(0).is_symbol(BOOL)
def is_literal ( self ) : if self . is_symbol ( BOOL ) : return True if self . is_not ( ) : return self . arg ( 0 ) . is_symbol ( BOOL )