code: func (p *Palette) functionColor(line *stack.Call) string {
  	if line.IsStdlib {
  		if line.Func.IsExported() {
  			return p.FuncStdLibExported
  		}
  		return p.FuncStdLib
  	} else if line.IsPkgMain() {
  		return p.FuncMain
  	} else if line.Func.IsExported() {
  		return p.FuncOtherExported
  	}
  	return p.FuncOther
  }
docs: // functionColor returns the color to be used for the function name based on
  // the type of package the function is in.