How to use the numexpr.expressions.OpNode function in numexpr

def truediv_op(a, b):
    if get_optimization() in ('moderate', 'aggressive'):
        if (isinstance(b, ConstantNode) and
                (a.astKind == b.astKind) and
                    a.astKind in ('float', 'double', 'complex')):
            return OpNode('mul', [a, ConstantNode(1. / b.value)])
    kind = commonKind([a, b])
    if kind in ('bool', 'int', 'long'):
        kind = 'double'
    return OpNode('div', [a, b], kind=kind)

def multiply(x, y):
                    if x is None: return y
                    return OpNode('mul', [x, y])

return ConstantNode(-self.value)

    def __invert__(self):
        return ConstantNode(~self.value)


class OpNode(ExpressionNode):
    astType = 'op'

    def __init__(self, opcode=None, args=None, kind=None):
        if (kind is None) and (args is not None):
            kind = commonKind(args)
        ExpressionNode.__init__(self, value=opcode, kind=kind, children=args)


class FuncNode(OpNode):
    def __init__(self, opcode=None, args=None, kind=None):
        if (kind is None) and (args is not None):
            kind = commonKind(args)
        OpNode.__init__(self, opcode, args, kind)

ishalfpower = int_(abs(2 * x)) % 2

                def multiply(x, y):
                    if x is None: return y
                    return OpNode('mul', [x, y])

                r = None
                p = a
                mask = 1
                while True:
                    if (n & mask):
                        r = multiply(r, p)
                    mask <<= 1
                    if mask > n:
                        break
                    p = OpNode('mul', [p, p])
                if ishalfpower:
                    kind = commonKind([a])
                    if kind in ('int', 'long'):
                        kind = 'double'
                    r = multiply(r, OpNode('sqrt', [a], kind))
                if r is None:
                    r = OpNode('ones_like', [a])
                if x < 0:
                    r = OpNode('div', [ConstantNode(1), r])
                return r
        if get_optimization() in ('moderate', 'aggressive'):
            if x == -1:
                return OpNode('div', [ConstantNode(1), a])
            if x == 0:
                return OpNode('ones_like', [a])
            if x == 0.5:

def operation(self, other):
        if reversed:
            self, other = other, self
        if allConstantNodes([self, other]):
            return ConstantNode(opfunc(self.value, other.value))
        else:
            return OpNode(opname, (self, other), kind=kind)

while True:
                    if (n & mask):
                        r = multiply(r, p)
                    mask <<= 1
                    if mask > n:
                        break
                    p = OpNode('mul', [p, p])
                if ishalfpower:
                    kind = commonKind([a])
                    if kind in ('int', 'long'):
                        kind = 'double'
                    r = multiply(r, OpNode('sqrt', [a], kind))
                if r is None:
                    r = OpNode('ones_like', [a])
                if x < 0:
                    r = OpNode('div', [ConstantNode(1), r])
                return r
        if get_optimization() in ('moderate', 'aggressive'):
            if x == -1:
                return OpNode('div', [ConstantNode(1), a])
            if x == 0:
                return OpNode('ones_like', [a])
            if x == 0.5:
                kind = a.astKind
                if kind in ('int', 'long'): kind = 'double'
                return FuncNode('sqrt', [a], kind=kind)
            if x == 1:
                return a
            if x == 2:
                return OpNode('mul', [a, a])
    return OpNode('pow', [a, b])

def get_imag(self):
        if self.astType == 'constant':
            return ConstantNode(complex(self.value).imag)
        return OpNode('imag', (self,), 'double')

def __neg__(self):
        return OpNode('neg', (self,))

def __init__(self, opcode=None, args=None, kind=None):
        if (kind is None) and (args is not None):
            kind = commonKind(args)
        OpNode.__init__(self, opcode, args, kind)