An algorithm is used to parse telemetry data from an oceanographic research buoy.
Figure 2
reading ← ""
k ← 0
WHILE raw_payload[k] ≠ "K" AND k < 8
reading ← reading + raw_payload[k]
k ← k + 1
ENDWHILE
is_valid ← False
IF reading ≠ "" AND k < 8 THEN
is_valid ← True
ENDIF
State the data type of the variable is_valid in the algorithm in Figure 2.