r a "__len__()"
method that returns zero, when called with the object. [1]  Here are
most of the built-in objects considered false:

* constants defined to be false: "None" and "False"

* zero of any numeric type: "0", "0.0", "0j", "Decimal(0)",
  "Fraction(0, 1)"

* empty sequences and collections: "''", "()", "[]", "{}", "set()",
  "range(0)"

Operations and built-in functions that have a Boolean result always
return "0" or "False" for false and "1" or "True" for true, unless
otherwise stated. (Important exception: the Boolean operations "or"
and "and" always return one of their operands.)
uż