Function binary_number_op 

pub unsafe fn binary_number_op(
    pc: *mut XmlXPathParserContext,
    op: impl Fn(f64, f64) -> f64,
)

Pop two number operands from the stack and apply op.

UPSTREAM-PARITY: the first popped value is the RIGHT operand (xmlXPathAddValues pops arg (rhs) then arg (lhs)).

SAFETY

• pc must be a valid parser context.