Doctor Class

local Person = require("Person") -- See: https://pastebin.com/DugLGsyg
local Doctor = setmetatable({}, {__index = Person})
Doctor.__index = Doctor

function Doctor.new(gender, name, field)
    local self = setmetatable(Person.new(gender, name), Doctor)
    self.field = field
    return self
end

function Doctor:greet()
    self:speak("Hello, I am Dr. " .. self.name)
end

function Doctor:heal(person)
    person.health = person.health + 10
    self:speak("Good thing you're not American or this would cost a fortune!")
    person:speak("Gee, thanks!")
end

return Doctor