- expr represents a constant expression
- range1 and range2 represent ranges (intervals)

- When its first operand is a constant expression expr, the operator in evaluates to true iff the constant value of the expression expr is contained in the interval range1.
- When both its operands are ranges (intervals), the operator in evaluates to true iff all values in range1 are contained in the interval range2.
- in is also used as a keyword for loops over the different elements of a list.

true

> 4 in [-1;1];

false

> 0 in sin([-17;17]);

true

true

> [2;3] in [4;5];

false

> [2;3] in [2.5;5];

false

1

2

3

4

5