instagram regex

def instacheck(name)

  unless /[a-z0-9._]{,30}/.match(name)
    return false
  end

  if /\.\./.match(name)
    return false
  end

  if /^\d+$/.match(name)
    return false
  end

  if /^\./.match(name)
    return false
  end

  true
end

My regex did no include any such characters. I can't comment on subsequent advice from anyone else. My code already checked for leading dots and did not fail any tests people brought up relating to someone elses code.