urequests: TypeError: object with buffer protocol required

r=urequest.post("http://www.example.com",headers={"Content-Length":19},data='{"hello":"world"}')
print(r.status_code,r.content)

Seems that that 19 is the issue and it needs to be a string, should the user of the lib be expected to know this or should this:

        for k in headers:
            s.write(k)
            s.write(b": ")
            s.write(headers[k])
            s.write(b"\r\n")

be changed to this:

        for k in headers:
            s.write(k)
            s.write(b": ")
            s.write(str(headers[k]))
            s.write(b"\r\n")

on a side note, why does this not happen with header={}
https://forums.raspberrypi.com/viewtopic.php?t=341355

Start by reproducing the posted request in python-ecosys/urequests/urequests.py, then read the header-writing loop around line 101 and compare how integer and string header values reach s.write(). Done means the expected handling of Content-Length=19 is established and the related header behavior is covered by the project’s available checks.