What does the statement 'if 'key' in dictionary:' do?

The statement 'if 'key' in dictionary:' is used to check for the existence of a specified key within a dictionary. In Python, dictionaries are collections of key-value pairs, and this statement allows you to determine whether a particular key is present in the dictionary.

When the condition evaluates to true, it indicates that the specified key exists, which can be useful for preventing errors before attempting to access or manipulate the associated value. For example, if you want to retrieve a value from the dictionary that corresponds to a specific key, checking for the key's existence beforehand helps to avoid a KeyError if the key is not found.

The other options do not accurately describe the functionality of this statement. It does not create or remove keys, nor does it assign values to a dictionary. Understanding this statement is fundamental when working with dictionaries in Python, as it forms the basis for safely accessing and managing data.