Add Enum to Schema generation

[stevebell117]

Hello, noticed that the enum logic was setup but not fully implemented so I went ahead and implemented it. I'm not super familiar with this repository, so I don't know how to fully test this but it worked well with the file I used against it (which I can attach, it's a bit large), but here's an example of the output I am now receiving after implementing it.

"assetType": {
"type": "string",
"enum": [
    "EQUITY",
    "OPTION",
    "INDEX",
    "MUTUAL_FUND",
    "CASH_EQUIVALENT",
    "FIXED_INCOME",
    "CURRENCY"
]

generates (See latest comment)

class Assettype(Enum):
    Equity = "EQUITY"
    Option = "OPTION"
    Index = "INDEX"
    Mutual_fund = "MUTUAL_FUND"
    Cash_equivalent = "CASH_EQUIVALENT"
    Fixed_income = "FIXED_INCOME"
    Currency = "CURRENCY"

I am concerned about backwards compatibility, as those who have used this library previously may not be able to handle the conversion from str to Enum (since they'd need to do .value. Would you recommend adding a argument to explicitly enable this behavior?

Addresses #19

[stevebell117]

The flake8 error that's being thrown doesn't make sense to me, but I'll continue looking in this more over the next few days.

[stevebell117]

Update:

The output now looks like:

Handles if no default is specified in the schema, and also includes a __str__ override to allow backwards compatibility.

No default:

self.session = None
if "session" in values:
    self.session = self.Session(values.get("session"))

class Session(Enum):
    Normal = "NORMAL"
    Am = "AM"
    Pm = "PM"
    Seamless = "SEAMLESS"

    def __str__(self):
        return str(self.value)