# File lib/heckle.rb, line 541
  def increment_mutation_count(node)
    # So we don't re-mutate this later if the tree is reset
    mutation_count[node] += 1
    mutatee_type = @mutatees[node.first]
    mutatee_type.delete_at mutatee_type.index(node)
    @mutated = true
  end