public boolean isArg(String prefix) {
        int n = prefix.length();
        if (n > 0 && prefix.charAt(n - 1) == '=') {
          // Argument accepts a value. Capture it.
          if (current.startsWith(prefix)) {
            // Argument is in the form --name=value, split the value out
            lastValue = current.substring(n);
            return true;
          } else {
            // Check whether we have "--name value" as 2 arguments
            prefix = prefix.substring(0, n - 1);
            if (current.equals(prefix)) {
              if (getNextValue()) {
                lastValue = current;
                return true;
              } else {
                System.err.println("Missing value after parameter " + prefix);
                throw new UsageException();
              }
            }
            return false;
          }
        } else {
          // Argument does not accept a value.
          return current.equals(prefix);
        }
      }
Checks the current argument against the given prefix. If prefix is in the form '--name=',
an extra value is expected. The argument can then be in the form '--name=value' or as a
2-argument form '--name value'.
android/android_framework/dex-maker/src/main/java/com/android/dx/command/dexer/Main.java