code: def verify_signature(message, key, signature):
      
      digest = hmac.new(key, msg=message, digestmod=hashlib.sha256).hexdigest()
      return digest == signature
docs: This function will verify the authenticity of a digital signature.
      For security purposes, Nylas includes a digital signature in the headers
      of every webhook notification, so that clients can verify that the
      webhook request came from Nylas and no one else. The signing key
      is your OAuth client secret, which only you and Nylas know.