
    Design a function for an adaptive learning system that analyzes a student's text response by calculating the total number of possible word combinations (including partial words) within their answer to assess language complexity. The count of these combinations (non-empty substrings) will be used to determine the appropriate difficulty level for subsequent questions in the learning module.
    

    
def number_of_substrings(str):
    """
    Design a function for an adaptive learning system that analyzes a student's text response by calculating the total number of possible word combinations (including partial words) within their answer to assess language complexity. The count of these combinations (non-empty substrings) will be used to determine the appropriate difficulty level for subsequent questions in the learning module.
    

    """
def number_of_substrings(str):
    """
    Design a function for an adaptive learning system that analyzes a student's text response by calculating the total number of possible word combinations (including partial words) within their answer to assess language complexity. The count of these combinations (non-empty substrings) will be used to determine the appropriate difficulty level for subsequent questions in the learning module.
    

    """
    str_len = len(str)
    return int(str_len * (str_len + 1) / 2)