## Providing the code I'm using for testing the API call:

import os
from google.cloud import language_v1

## Set Google API Key
os.environ.get("GOOGLE_APPLICATION_CREDENTAILS")

client = language_v1.LanguageServiceClient()

def categorize(txt):
    """
    Takes a string as an argument and returns the category with highest confidence received from the Google NLP API.
    """
    result = {}

    document = language_v1.Document(content = txt, type_=language_v1.types.Document.Type.PLAIN_TEXT)
    content_categories_version = (language_v1.ClassificationModelOptions.V2Model.ContentCategoriesVersion.V2)
    request_json = {
        "document": document,
        "classification_model_options": {
            "v2_model": {
                "content_categories_version": content_categories_version
                }
            }
        }

    response = client.classify_text(request=request_json)
    print(response)

    for category in response.categories:
        result[category.name] = category.confidence
    
    print(result)

    best_response = max(result, key = result.get)

    lst = best_response.split(sep = '/')
    out_category = lst[-1]
          
    return out_category

txt = 'Dungeons and Dragons'

categorize(txt)