Micrograd subtraction gradient is wrong

[backsideofdawn]

I'm not very experienced with calculus, but my intuition along with ChatGPT tells me that this is wrong:

def __sub__(self, other):
    other = Value(other) if not isinstance(other, Value) else other
    out = Value(self.data - other.data, (self, other), '-')
    def _backward():
        self.grad += 1.0 * out.grad
        other.grad += 1.0 * out.grad
    out._backward = _backward
    return out

Shouldn't the gradient of other be other.grad += -1.0 * out.grad?