<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def str2fl(x):
 """Recurses through lists and converts lists of string to float Args: x: string or list of strings """

    def helper_to_fl(s_):
        """ deals with odd string imports converts to float"""
        if s_ == "":
            return "null"
        elif "," in s_:
            s_ = s_.replace(",", "")

        try:
            return float(s_)
        except:
            return (s_)

    fl_lst = []
    if isinstance(x[0], str):                # Check if list of strings, then sent to conversion
        for xi in range(len(x)):
            fl_lst.append(helper_to_fl(x[xi]))
    elif isinstance(x[0], list):                    # Check if list of lists, then recurse
        for xi in range(len(x)):
            fl_lst.append(str2fl(x[xi]))
    else:
        return False

    return fl_lst