String

  public fun is_valid_name(
      name: &String,
      min_length: u64,
      max_length: u64
  ): bool {
      let len = name.length();
      let name_bytes = name.as_bytes();
      let mut index = 0;

      if (!(len >= min_length && len <= max_length)) {
          return false
      };

      while (index < len) {
          let character = name_bytes[index];
          let is_valid_character =
              (CHAR_UPPER_A <= character && character <= CHAR_UPPER_Z)
              || (CHAR_LOWER_A <= character && character <= CHAR_LOWER_Z)
              || (CHAR_ZERO <= character && character <= CHAR_NINE)
              || (character == CHAR_DASH && index != 0 && index != len - 1);

          if (!is_valid_character) {
              return false
          };

          index = index + 1;
      };

      true
  }

  public fun to_lowercase(
      name: &String
  ): String {
      let len = name.length();
      let name_bytes = name.as_bytes();
      let mut index = 0;

      let mut lowercase_bytes = vector::empty<u8>();

      while (index < len) {
          let character = name_bytes[index];

          let lowercase = if (
              CHAR_UPPER_A <= character && character <= CHAR_UPPER_Z
          ) {
              character + CHAR_CASE_OFFSET
          } else {
              character
          };

          lowercase_bytes.push_back(lowercase);

          index = index + 1;
      };

      utf8(lowercase_bytes)
  }

  public fun to_uppercase(
      name: &String
  ): String {
      let len = name.length();
      let name_bytes = name.as_bytes();
      let mut index = 0;

      let mut lowercase_bytes = vector::empty<u8>();

      while (index < len) {
          let character = name_bytes[index];

          let lowercase = if (
              CHAR_LOWER_A <= character && character <= CHAR_LOWER_Z
          ) {
              character - CHAR_CASE_OFFSET
          } else {
              character
          };

          lowercase_bytes.push_back(lowercase);

          index = index + 1;
      };

      utf8(lowercase_bytes)
  }