def sign(time)
      unencrypted_signature = @api_key + @secret + time + @user.to_s
      to_digest = unencrypted_signature + unencrypted_signature.length.to_s
      return Digest::MD5.hexdigest(to_digest)
    end
def sign(time)
      unencrypted_signature = @api_key + @secret + time + @user.to_s
      to_digest = unencrypted_signature + unencrypted_signature.length.to_s
      return Digest::MD5.hexdigest(to_digest)
    end
Method for constructing a signature