How do I check if an object is of a given type, or if it inherits from a given type?
How do I check if the object o is of type str?
Editor's note: Beginners often wrongly expect a string to already be "a number" – either expecting Python 3.x input to convert type, or expecting that a string like '1' is also simultaneously an integer. This question does not address those types of questions. Instead, see How do I check if a string represents a number (float or int)?, How can I read inputs as numbers? and/or Asking the user for input until they give a valid response as appropriate.