const left = {
  alpha: "1"
}
const right = {
  beta: "2"
}

mergeDeepLeft(left)(right)
{
  alpha: "1",
  beta: "2"
}

const left = {
  alpha: {
    alpha1: "1"
  }
}
const right = {
  beta: {
    beta1: "1"
  }
}

mergeDeepLeft(left)(right)
{
  alpha: {
    alpha1: "1"
  },
  beta: {
    beta1: "1"
  }
}

const left = {
  alpha: [
    "1"
  ]
}
const right = {
  alpha: [
    "1"
  ]
}

mergeDeepLeft(left)(right)
{
  alpha: [
    "1",
    "1"
  ]
}