Boolean expressions
Comparison operators:
<, <=, ==, >=, >
a<b<c     a<b and b<c
Containment operator
a in b; a not in b
Boolean expressions:
Short circuiting
a and b    # a if a is false, else b
a or b     # a if a is true, else b
not a      # 1 if a false, else 0