original_string: public function getHeader($keyName)
      {
          $headers = $this->getHeaders();
          $keyName = self::normalizeHeaderKeyName($keyName);
          if (array_key_exists($keyName, $headers)) {
              return $headers[$keyName];
          }
  
          return;
      }
code: public function getHeader($keyName)
      {
          $headers = $this->getHeaders();
          $keyName = self::normalizeHeaderKeyName($keyName);
          if (array_key_exists($keyName, $headers)) {
              return $headers[$keyName];
          }
  
          return;
      }
code_tokens: public function getHeader ( $ keyName ) { $ headers = $ this -> getHeaders ( ) ; $ keyName = self :: normalizeHeaderKeyName ( $ keyName ) ; if ( array_key_exists ( $ keyName , $ headers ) ) { return $ headers [ $ keyName ] ; } return ; }
docstring: Get the value of the request header keyname.
  
  @param string $keyName the HTTP header keyname
  
  @return mixed the value of the header keyname as string or null if the
  header key is not set
docstring_tokens: Get the value of the request header keyname .