onlineParser/client_code/Form1/__init__.py

from ._anvil_designer import Form1Template
from anvil import *
import anvil.tables as tables
import anvil.tables.query as q
from anvil.tables import app_tables
import yaml

class Form1(Form1Template):
  def __init__(self, **properties):
    # Set Form properties and Data Bindings.
    self.init_components(**properties)

    # Any code you write here will run when the form opens.

  def check_click(self, **event_args):
    """This method is called when the button is clicked"""
    print(yaml.safe_load(self.yaml_input.text))