The pyeval function is not treated as a system function

[dsawardekar]

Using the viml native pyeval function results in a script local function call s:pyeval. This gives a runtime error, s:pyeval not found when running the generated viml.

Given the Riml,

result = pyeval('{ "foo": 1 }')

Gives the output Viml,

let s:result = s:pyeval('{ "foo": 1 }')

It should be just pyeval.