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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_terminal_size(fallback=(80, 24)):
 """Get the size of the terminal window. For each of the two dimensions, the environment variable, COLUMNS and LINES respectively, is checked. If the variable is defined and the value is a positive integer, it is used. When COLUMNS or LINES is not defined, which is the common case, the terminal connected to sys.__stdout__ is queried by invoking os.get_terminal_size. If the terminal size cannot be successfully queried, either because the system doesn't support querying, or because we are not connected to a terminal, the value given in fallback parameter is used. Fallback defaults to (80, 24) which is the default size used by many terminal emulators. The value returned is a named tuple of type os.terminal_size. """

    # Try the environment first
    try:
        columns = int(os.environ["COLUMNS"])
    except (KeyError, ValueError):
        columns = 0

    try:
        lines = int(os.environ["LINES"])
    except (KeyError, ValueError):
        lines = 0

    # Only query if necessary
    if columns <= 0 or lines <= 0:
        try:
            size = _get_terminal_size(sys.__stdout__.fileno())
        except (NameError, OSError):
            size = terminal_size(*fallback)

        if columns <= 0:
            columns = size.columns
        if lines <= 0:
            lines = size.lines

    return terminal_size(columns, lines)