class_docstr: Converts string into MongoQuery
code: def from_string(self, call_str):
      tree = py_ast.parse(call_str.strip(), mode="eval")
      calls = self.process(tree.body)
      # first call contents collection
      method1 = calls[0]["method"]
      if len(method1) < 2:
          raise IndexError("Collection not found")
      collection = method1[-2]
  
      mquery = MongoQuery(collection)
  
      # keep only last name
      calls[0]["method"] = [method1[-1]]
  
      # convert method names: get first item of list
      for c in calls:
          mquery.add_step({"method": c["method"][0], "args": c["args"]})
  
      return mquery
  
imports: import ast
  import dateutil.parser
  from bson import ObjectId
  from .mongodb_query import MongoQuery
label_desc: Use image node_id 1 for calling the MongodbParser obj's underlying member method code with example usage: obj.from_string(call_str) and returns: mquery