def _call(self, x, out=None):
        """Linearly combine ``x`` and write to ``out`` if given."""
        if out is None:
            out = self.range.element()
        out.lincomb(self.a, x[0], self.b, x[1])
        return out
def _call ( self , x , out = None ) : if out is None : out = self . range . element ( ) out . lincomb ( self . a , x [ 0 ] , self . b , x [ 1 ] ) return out
Linearly combine ``x`` and write to ``out`` if given.