code: def common(self, other):
  		'''
  			Return the common part of these two mults. This is the largest mult
  			which can be safely subtracted from both the originals. The multiplier
  			on this mult could be zero: this is the case if, for example, the
  			multiplicands disagree.
  		'''
  		if self.multiplicand == other.multiplicand:
  			return mult(self.multiplicand, self.multiplier.common(other.multiplier))
  
  		# Multiplicands disagree, no common part at all.
  		return mult(nothing, zerof common(self, other):
  		'''
  			Return the common part of these two mults. This is the largest mult
  			which can be safely subtracted from both the originals. The multiplier
  			on this mult could be zero: this is the case if, for example, the
  			multiplicands disagree.
  		'''
  		if self.multiplicand == other.multiplicand:
  			return mult(self.multiplicand, self.multiplier.common(other.multiplier))
  
  		# Multiplicands disagree, no common part at all.
  		return mult(nothing, zero)
docs: Return the common part of these two mults. This is the largest mult
  			which can be safely subtracted from both the originals. The multiplier
  			on this mult could be zero: this is the case if, for example, the
  			multiplicands disagree.