// complex128 for float64).
func complex(r, i FloatType) ComplexType

// The real built-in function returns the real part of the complex number c.
// The return value will be floating point type corresponding to the type of c.
func real(c ComplexType) FloatType

// The imag built-in function returns the imaginary part of the complex
// number c. The return value will be floating point type corresponding to
// the type of c.