Nested BinOpExpr returns the incorrect query.

[gwdawson]

when using more than one BinOpExpr, the returned query is incorrect.
looking at the example, you can see that the first expr is duplicated and the third one is lost.

QUERY:
rate({one=""}[1m]) + rate({two=""}[5m]) + rate({three=""}[10m])


EXPECTED:
rate(
  {one=""}
  [1m]
)
+
rate(
  {two=""}
  [5m]
)
+
rate(
  {three=""}
  [10m]
)


ACTUAL:
rate(
  {one=""}
  [1m]
)
+
rate(
  {two=""}
  [5m]
)
+
rate(
  {one=""}
  [1m]
)