Int128.opOpAssign

Int128 opOpAssign(string op)(Int128 op2) if (op ==  "+" ||  op ==  "-" ||
         op ==  "*" ||  op ==  "/" ||  op ==  "%" ||
         op ==  "&" ||  op ==  "|" ||  op ==  "^" ||
         op ==  "<<" ||  op ==  ">>" ||  op ==  ">>>")

ref

arithmetic assignment operators += -= *= /= %= &= |= ^= <<= >>= >>>=

Parameters

`op`	one of +, -, etc.
`op2`	second operand

Returns

lvalue of updated left operand

Int128 opOpAssign(string op,  Int)(auto  ref  Int op2) if ((op ==  "+" ||  op ==  "-" ||
         op ==  "*" ||  op ==  "/" ||  op ==  "%" ||
         op ==  "&" ||  op ==  "|" ||  op ==  "^" ||
         op ==  "<<" ||  op ==  ">>" ||  op ==  ">>>")
         &&  is(Int :  long))

ref

ditto