{
  
  # Here's the list of organization IDs.
  # I don't know if there's a limit to these lists.
  # Any time you see a plural ("nodes") it *usually* means we're
  # about to loop over a result set. But I think this is implementer
  # convention; "nodes" and "edges" are GraphQL reserved words, but
  # most of the rest aren't.
  # For the moment, I've only put two organization IDs in here.
  nodes(ids: ["MDEyOk9yZ2FuaXphdGlvbjYyMzM5OTQ=", "MDEyOk9yZ2FuaXphdGlvbjY0MzA3MA=="]) {
    
    # Join to a nested list of organization objects.
    id
    ... on Organization {
      name # The organization name

      # Further nesting: Repos.
      # Only asking for 100 because that's a GitHub-set limit.
      # When you want to filter the set of objects returned, it
      # seems to be done in this kind of way - as arguments to
      # the node list. So here, we're filtering for public repos.
      repositories(first: 100, privacy: PUBLIC) {
        nodes {
          
          # Metadata about the repos. I'm only fetching a few values
          # but I could, in theory, go wild with sub-queries about
          # contributors, pull requests, etc.
          # This is ALL coming back in this ONE query.
          name
          createdAt
          url
          homepageUrl
          languages(first:5) {
            nodes {
              name
            }
          }
          pullRequests(first:5, states:[OPEN]) {
            nodes {
              author {
              	login
              }
              title
            }
          }
        }
      }
    }
  }
  
  # All the useful repo data is up above.
  # This following section is cost data about the query itself.
  # The GitHub GraphQL API gives API users a limited hourly budget,
  # in "points", to stop the system being overloaded. Every time 
  # you execute a query, it subtracts the cost from your remaining 
  # budget for the hour.
  
  # If you're experimenting with big queries, I recommend adding
  # this block to the *beginning* of your query, so you can keep
  # an eye on things. Remember that a low query cost becomes a 
  # problem when you're doing a few hundred of these an hour.
  # For more information: https://developer.github.com/v4/guides/resource-limitations/
  
  rateLimit {
    limit     # Your maximum budget. Your budget is reset to this every hour.
    cost      # The cost of this query.
    remaining # How much of your API budget remains.
    resetAt   # The time (in UTC epoch seconds) when your budget will reset.
  }
}

# If it wasn't for the 100-node-per-list limit, we'd be able to get
# *all* the repos for each organization with this query. Instead,
# we need to do a series of queries which page through the repos,
# a hundred at a time. However, note that we're actually getting 200
# repos back with this query - 100 per org. So the current plan is
# to provide the org IDs for each gov org in GitHub (30 or so) and
# list them all in the query, so we get up to 3000 repos back.
#
# So it's kind of horizontally-slicing across the org structure.
#
# (We've had some conversations with GitHub folks and they say that
# this kind of query behaviour is fine, as long as we keep an eye
# on our query cost limits.)

# Future work:
#
# Would it be possible to provide the list of organization IDs in
# a GraphQL variable rather than hardcoded into the query?