Make an easy function for converting token balance integers to decimal token values [APE-1114]

[fubuloubu]

Overview

It would be nice to render a token value back to a human-readable amount

Specification

from ape_tokens import tokens

weth = tokens["WETH"]

# Look up conversion factor by symbol
assert tokens.render(weth.balanceOf(acct), "WETH") == "1.27 WETH"
# OR allow using any token contract (which has `.symbol()` and `.decimals()` methods)
assert tokens.render(weth.balanceOf(acct), weth) == "1.27 WETH"