public function getHeader($keyName)
    {
        $headers = $this->getHeaders();
        $keyName = self::normalizeHeaderKeyName($keyName);
        if (array_key_exists($keyName, $headers)) {
            return $headers[$keyName];
        }

        return;
    }
public function getHeader($keyName)
    {
        $headers = $this->getHeaders();
        $keyName = self::normalizeHeaderKeyName($keyName);
        if (array_key_exists($keyName, $headers)) {
            return $headers[$keyName];
        }

        return;
    }
public function getHeader ( $ keyName ) { $ headers = $ this -> getHeaders ( ) ; $ keyName = self :: normalizeHeaderKeyName ( $ keyName ) ; if ( array_key_exists ( $ keyName , $ headers ) ) { return $ headers [ $ keyName ] ; } return ; }
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
Get the value of the request header keyname .