### 9.5. `FoDim.__mul__()`

: Multiply by a
constant

We implement the multiply operator only for cases where the
right-hand operator is a number (not a `FoDim`

).
A length times a length is an area, but this class deals only
in lengths.

fohelpers.py

# - - - F o D i m . _ _ m u l _ _
def __mul__ ( self, other ):
'''Multiply self by a constant.
'''
return FoDim ( self.n * Decimal(other), self.units )