<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def iterate_ngrams(text, n):
 """Generator to yield ngrams in ``text``. Example: exam xamp ampl mple Args: text (str):
 text to iterate over n (int):
 size of window for iteration Returns: Generator expression to yield the next ngram in the text Raises: ValueError: If n is non positive """

    if n <= 0:
        raise ValueError("n must be a positive integer")

    return [text[i: i + n] for i in range(len(text) - n + 1)]