I have a JavaScript on GEE's code editor that allows me to download a collection of Landsat images with a cloud filter directly applied (meaning that I download only the images with less than a certain percentage of cloud cover). I would like to translate the code to Python but I don't know how to deal with the custom cloud function: In JavaScript, the cloud condition (less than x% of clouds to be in the collection) is called without any variable, directly in the ee.collection() command. In Python, I don't know how to make it work because there is no variable yet, it seems that I have to download the image first, and then apply the cloud percentage calculation (and then dump my image if it fails to meet the requirements).

Is there a way on Python to download Landsat images already filtered depending on their cloud cover ?

My JavaScript code is:

var geometry: Polygon, 4 vertices
type: 
Polygon
coordinates: 
List (1 element)
0: 
List (5 elements)
0: 
[-141.0073440277409,59.69885769939182]
1: 
[-140.12569119570966,59.69885769939182]
2: 
[-140.12569119570966,60.16125006608516]
3: 
[-141.0073440277409,60.16125006608516]
4: 
[-141.0073440277409,59.69885769939182]
0: 
-141.0073440277409
1: 
59.69885769939182
geodesic: 
false

var cloudMaskL457 = function(image) {
  var qa = image.select('pixel_qa');
  // If the cloud bit (5) is set and the cloud confidence (7) is high
  // or the cloud shadow bit is set (3), then it's a bad pixel.
  var cloud = qa.bitwiseAnd(1 << 5)
                  .and(qa.bitwiseAnd(1 << 7))
                  .or(qa.bitwiseAnd(1 << 3));
  // Remove edge pixels that don't occur in all bands
  var mask2 = image.mask().reduce(ee.Reducer.min());
  return image.updateMask(cloud.not()).updateMask(mask2);
};

var l5 = ee.ImageCollection('LANDSAT/LT05/C01/T1_SR')
                  .filterDate('1984-01-01', '2012-05-05')
                  .map(cloudMaskL457)
                  .filterBounds(aoi)
                  .map(function(a){
                    return a.set('year', ee.Image(a).date().get('year'))
                  })

Ps: I already use code for Sentinel-2 downloading that has a specific built-in function. I failed to find something similar for Landsat.

S2_collection = ee.ImageCollection('COPERNICUS/S2').filterBounds(polytest).filter(ee.Filter.lessThanOrEquals('CLOUDY_PIXEL_PERCENTAGE', 10)).filter(ee.Filter.date(sdate, edate))