def check_freq(dict_to_check, text_list):
    """
    Checks each given word's freqency in a list of posting strings.

    Params:
        words: (dict) a dict of word strings to check frequency for, format:
            {'languages': ['Python', 'R'..],
            'big data': ['AWS', 'Azure'...],
             ..}
        text_list: (list) a list of posting strings to search in

    Returns:
        freq: (dict) frequency counts

    """
    freq = {}

    # Join the text together and convert words to lowercase 
    text = ' '.join(text_list).lower()

    for category, skill_list in dict_to_check.items():
        # Initialize each category as a dictionary
        freq[category] = {}
        for skill in skill_list:
            if len(skill) == 1: # pad single letter skills such as "R" with spaces
                skill_name = ' ' + skill.lower() + ' '
            else:
                skill_name = skill.lower()    
            freq[category][skill] = text.count(skill_name)

    return freq