src/AbstractSerializer.php
protected static function serializeHeaders(array $headers)
    {
        $lines = [];
        foreach ($headers as $header => $values) {
            $normalized = self::filterHeader($header);
            foreach ($values as $value) {
                $lines[] = sprintf('%s: %s', $normalized, $value);
            }
        }

        return implode("\r\n", $lines);
    }
protected static function serializeHeaders(array $headers)
    {
        $lines = [];
        foreach ($headers as $header => $values) {
            $normalized = self::filterHeader($header);
            foreach ($values as $value) {
                $lines[] = sprintf('%s: %s', $normalized, $value);
            }
        }

        return implode("\r\n", $lines);
    }
protected static function serializeHeaders ( array $ headers ) { $ lines = [ ] ; foreach ( $ headers as $ header => $ values ) { $ normalized = self :: filterHeader ( $ header ) ; foreach ( $ values as $ value ) { $ lines [ ] = sprintf ( '%s: %s' , $ normalized , $ value ) ; } } return implode ( "\r\n" , $ lines ) ; }
Serialize headers to string values.

@param array $headers
@return string
Serialize headers to string values .