Fix printing an expression with fractional cost.
Fix printing an expression with fractional cost.

MadBomber/link-grammar,MadBomber/link-grammar,ampli/link-grammar,MadBomber/link-grammar,opencog/link-grammar,MadBomber/link-grammar,opencog/link-grammar,linas/link-grammar,ampli/link-grammar,opencog/link-grammar,MadBomber/link-grammar,linas/link-grammar,opencog/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,ampli/link-grammar,ampli/link-grammar,ampli/link-grammar,opencog/link-grammar,linas/link-grammar,linas/link-grammar,opencog/link-grammar,MadBomber/link-grammar,opencog/link-grammar,ampli/link-grammar,ampli/link-grammar,linas/link-grammar,MadBomber/link-grammar,MadBomber/link-grammar,linas/link-grammar,linas/link-grammar,linas/link-grammar,linas/link-grammar