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

for name in c.co_names:
            if name == "None":
                names[name] = None
            elif name == "True":
                names[name] = True
            elif name == "False":
                names[name] = False
            else:
                t = types.get(name, default_type)
                names[name] = expressions.VariableNode(name, type_to_kind[t])
        names.update(expressions.functions)
        # now build the expression
        ex = eval(c, names)
        if expressions.isConstant(ex):
            ex = expressions.ConstantNode(ex, expressions.getKind(ex))
        elif not isinstance(ex, expressions.ExpressionNode):
            raise TypeError("unsupported expression type: %s" % type(ex))
    finally:
        expressions._context.set_new_context(old_ctx)
    return ex

__rrshift__ = binop('rshift', reversed=True)

    # boolean operations

    __and__ = binop('and', kind='bool')
    __or__ = binop('or', kind='bool')

    __gt__ = binop('gt', kind='bool')
    __ge__ = binop('ge', kind='bool')
    __eq__ = binop('eq', kind='bool')
    __ne__ = binop('ne', kind='bool')
    __lt__ = binop('gt', reversed=True, kind='bool')
    __le__ = binop('ge', reversed=True, kind='bool')


class LeafNode(ExpressionNode):
    leafNode = True


class VariableNode(LeafNode):
    astType = 'variable'

    def __init__(self, value=None, kind=None, children=None):
        LeafNode.__init__(self, value=value, kind=kind)


class RawNode(object):
    """Used to pass raw integers to interpreter.
    For instance, for selecting what function to use in func1.
    Purposely don't inherit from ExpressionNode, since we don't wan't
    this to be used for anything but being walked.
    """

def _equiv_expr_node(x, y):
    """Returns whether two ExpressionNodes are equivalent.

    This is needed because '==' is overridden on ExpressionNode to
    return a new ExpressionNode.

    """
    if not isinstance(x, ExpressionNode) and not isinstance(y, ExpressionNode):
        return x == y
    elif (type(x) is not type(y) or not isinstance(x, ExpressionNode)
            or not isinstance(y, ExpressionNode)
            or x.value != y.value or x.astKind != y.astKind
            or len(x.children) != len(y.children)):
        return False
    for xchild, ychild in zip(x.children, y.children):
        if not _equiv_expr_node(xchild, ychild):
            return False
    return True

def func(*args):
        args = list(args)
        for i, x in enumerate(args):
            if isConstant(x):
                args[i] = x = ConstantNode(x)
            if not isinstance(x, ExpressionNode):
                raise TypeError("unsupported object type: %s" % type(x))
        return f(*args)

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)

def __init__(self, value=None, children=None):
        kind = getKind(value)
        # Python float constants are double precision by default
        if kind == 'float':
            kind = 'double'
        LeafNode.__init__(self, value=value, kind=kind)

    def __neg__(self):
        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)