Checkbox select all depending on form ID

JS

function toggle(source) {
  checkboxes = document.getElementsByName("foo");
  for(var i=0; i < checkboxes.length; i++) {
    checkboxes[i].checked = source.checked;
  }
}

I have 3 forms with each ID

<form id="one">  
    <fieldset>  
    <legend>Select Quarter / 2017</legend> 
    <input type="checkbox" name="foo" onClick="toggle(this)" />All<br/>
    <input type="checkbox" name="foo" >Q1 2017<br>  
    <input type="checkbox" name="foo" >Q2 2017<br>  
    <input type="checkbox" name="foo" >Q3 2017<br> 
    <input type="checkbox" name="foo" >Q4 2017<br>   
    </fieldset>
</form>  

<form id="two">  
    <fieldset>  
    <legend>Select Quarter / 2017</legend> 
    <input type="checkbox" name="foo" onClick="toggle(this)" />All<br/>
    <input type="checkbox" name="foo" >Q1 2017<br>  
    <input type="checkbox" name="foo" >Q2 2017<br>  
    <input type="checkbox" name="foo" >Q3 2017<br> 
    <input type="checkbox" name="foo" >Q4 2017<br>   
    </fieldset>
</form>  

<form id="three">  
    <fieldset>  
    <legend>Select Quarter / 2017</legend> 
    <input type="checkbox" name="foo" onClick="toggle(this)" />All<br/>
    <input type="checkbox" name="foo" >Q1 2017<br>  
    <input type="checkbox" name="foo" >Q2 2017<br>  
    <input type="checkbox" name="foo" >Q3 2017<br> 
    <input type="checkbox" name="foo" >Q4 2017<br>   
    </fieldset>
</form>  

I want to use the same javascript function to target the three different select all forms according to ID. With this function I now toggle all checkboxes, but I want to toggle all checkboxes in each form, so I don't toggle all checkboxes in all three forms at the same time. How can I do that?