code: @Override
  	public Constant getVal(String fldName) {
  		if (s1.hasField(fldName))
  			return s1.getVal(fldName);
  		else
  			return s2.getVal(fldName);
  	}
docs: Returns the value of the specified field. The value is obtained from
  whichever scan contains the field.
  
  @see Scan#getVal(java.lang.String)