code: public static boolean isAsciiPrintable(final CharSequence cs) {
          if (cs == null) {
              return false;
          }
          final int sz = cs.length();
          for (int i = 0; i < sz; i++) {
              if (!CharUtils.isAsciiPrintable(cs.charAt(i))) {
                  return false;
              }
          }
          return true;
      }
docs: <p>Checks if the CharSequence contains only ASCII printable characters.</p>
  
  <p>{@code null} will return {@code false}.
  An empty CharSequence (length()=0) will return {@code true}.</p>
  
  <pre>
  StringUtils.isAsciiPrintable(null)     = false
  StringUtils.isAsciiPrintable("")       = true
  StringUtils.isAsciiPrintable(" ")      = true
  StringUtils.isAsciiPrintable("Ceki")   = true
  StringUtils.isAsciiPrintable("ab2c")   = true
  StringUtils.isAsciiPrintable("!ab-c~") = true
  StringUtils.isAsciiPrintable("\u0020") = true
  StringUtils.isAsciiPrintable("\u0021") = true
  StringUtils.isAsciiPrintable("\u007e") = true
  StringUtils.isAsciiPrintable("\u007f") = false
  StringUtils.isAsciiPrintable("Ceki G\u00fclc\u00fc") = false
  </pre>
  
  @param cs the CharSequence to check, may be null
  @return {@code true} if every character is in the range
  32 thru 126
  @since 2.1
  @since 3.0 Changed signature from isAsciiPrintable(String) to isAsciiPrintable(CharSequence)