code: protected function chainMockReturns()
      {
          $code  = "    function returns(\$method, \$value, \$args = false) {\n";
          $code .= $this->bailOutIfNotMocked('$method');
          $code .= "        \$this->mock->returns(\$method, \$value, \$args);\n";
          $code .= "    }\n";
          $code .= "    function returnsAt(\$timing, \$method, \$value, \$args = false) {\n";
          $code .= $this->bailOutIfNotMocked('$method');
          $code .= "        \$this->mock->returnsAt(\$timing, \$method, \$value, \$args);\n";
          $code .= "    }\n";
          $code .= "    function returnsByValue(\$method, \$value, \$args = false) {\n";
          $code .= $this->bailOutIfNotMocked('$method');
          $code .= "        \$this->mock->returns(\$method, \$value, \$args);\n";
          $code .= "    }\n";
          $code .= "    function returnsByValueAt(\$timing, \$method, \$value, \$args = false) {\n";
          $code .= $this->bailOutIfNotMocked('$method');
          $code .= "        \$this->mock->returnsByValueAt(\$timing, \$method, \$value, \$args);\n";
          $code .= "    }\n";
          $code .= "    function returnsByReference(\$method, &\$ref, \$args = false) {\n";
          $code .= $this->bailOutIfNotMocked('$method');
          $code .= "        \$this->mock->returnsByReference(\$method, \$ref, \$args);\n";
          $code .= "    }\n";
          $code .= "    function returnsByReferenceAt(\$timing, \$method, &\$ref, \$args = false) {\n";
          $code .= $this->bailOutIfNotMocked('$method');
          $code .= "        \$this->mock->returnsByReferenceAt(\$timing, \$method, \$ref, \$args);\n";
          $code .= "    }\n";
  
          return $code;
      }
docs: Creates source code for chaining to the composited mock object.
  
  @return string Code for mock set up.