/* VarExpr.java */

import java.util.*;  

/* A class representing variables. */
public class VarExpr extends Expression {
  
  public VarExpr(String s) {
    /* Fill in for part 2. */
  }

  public int arity() {
    return 0;
  }

  public void set(Value V) {
    /* Fill in for part 2. */
  }

  public String toString() {
    /* Fill in for part 2. */
  }

  public Value eval() {
    /* Fill in for part 2. */
  }
}