Nimongo comparison (i.e. $gt) queries

[rustomax]

I can't figure out how to do comparison queries with Nimongo. Would appreciate 
any solutions.
    
    
    import oids
    
    import nimongo/bson  ## MongoDB BSON serialization/deserialization
    import nimongo/mongo ## MongoDB client
    
    ## Create new Mongo client
    var m = newMongo()
    
    ## Connect to Mongo server
    let connectResult = m.connect()
    
    ## Specify collection
    let collection = m["db"]["weather"]
    
    ## Create new bson document
    let weather_item = %*{
      "_id": $genOid(),
      "temp": 15.6,
      "feels_like": 14.5,
      "units": "C"
    }
    
    ## Insert document into DB
    collection.insert(weather_item)
    
    ## Fetch number of weather items
    let num_wi = collection.find(%*{}).count()
    echo "# of weather items: ", num_wi
    
    # tried different variations of the query below, but still can't get the 
correct behavior
    let query = B("temp", "{$gt:10}".toBson)
    echo query
    
    let temps_over_10C = collection.find(query)
    let tn = temps_over_10C.count()
    
    echo "Found ", tn, " records with temp over 10C"
    for temp in temps_over_10C:
      echo "temp = ", temp
    
    # Output:
    # # of weather items: 4
    # {
    #     "temp" : "{$gt:10}"
    # }
    # Found 0 records with temp over 10C
    
    
    Run

The records are correctly inserted into mongo (from multiple runs). And I am 
confident the find syntax is correct as the same command works from the mongo 
shell: 
    
    
    > db.weather.find({"temp": {$gt:10}})
    { "_id" : "5cbf2625e269b85d096176b6", "temp" : 15.6, "feels_like" : 14.5, 
"units" : "C" }
    { "_id" : "5cbf299d4fded4440a4531fe", "temp" : 15.6, "feels_like" : 14.5, 
"units" : "C" }
    
    
    Run

I suspect it has to do with additional double quotes being inserted into the 
filter, but I am not sure how to force nimongo to do without them: 
    
    
    > db.weather.find({"temp": "{$gt:10}"}).count()
    0
    
    
    Run