Update app.py

app.py

@@ -5,6 +5,8 @@ from langchain.prompts import HumanMessagePromptTemplate, ChatPromptTemplate
 from langchain.output_parsers import PydanticOutputParser
 from langchain_openai import ChatOpenAI
 
+# define the model instance
+chat = ChatOpenAI()
 
 class TextTranslator(BaseModel):
     output_text: str = Field(description="Python string containing the output text translated in the desired language")