[BUG-REPORT] Vaex can't handle Enums being used to reference columns

[Ben-Epstein]

Description

import vaex
from enum import Enum, unique

@unique
class Col(str, Enum):
    id = "id"
    x = "x"

df = vaex.from_dict({
    Col.x: list(range(10)),
    Col.id: list(range(10, 20)),
})
df

ValueError: Unknown expression type: <class 'ast.Attribute'>

You need to do

df = vaex.from_dict({
    Col.x.value: list(range(10)),
    Col.id.value: list(range(10, 20)),
})

Which shouldn't be because we defined the class to inherit from str first.

Software information

• Vaex version (import vaex; vaex.__version__):
• Vaex was installed via: pip / conda-forge / from source
• OS:

Additional information Please state any supplementary information or provide additional context for the problem (e.g. screenshots, data, etc..).