function string:lstrip()
  return self:gsub("^%s+", "")
  end
function string:rstrip()
  return self:gsub("%s+$", "")
  end
function string:strip()
  local h1
  h1 = self:lstrip()
  return h1:rstrip()
  end
function string:startswith(text)
  local size = text:len()
  if self:sub(1, size) == text then
    return self
    end
  end
function string:endswith(text)
  if self:sub(-#text) == text then
    return self
    end
  end
