title: Datadog: Use a tag value in an alias
body: <p>I have a timeseries graph in a time board that displays data for one metric that has multiple tags called "page". The graph has one line for each tag and I'm running functions on the values, so the query for my data is "ewma_5(avg:client.load_time{env:prod}) by {page}". This query means the tooltip values when I hover on the graph are things like "ewma_5(avg:client.load_time{env:prod})".</p>
  
  <p>I want to know if there is anyway to use the alias function with the tag value in it, so something like "alias": "{page}"?</p>