+timeUntilNextDay(){
+    # Desc: Report seconds until next day.
+    # Version: 1.0.2
+    # Output: stdout: integer seconds until next day
+    # Output: exit code 0 if stdout > 0; 1 if stdout = 0; 2 if stdout < 0
+    # Usage: timeUntilNextDay
+    # Usage: if ! myTTL="$(timeUntilNextDay)"; then yell "ERROR in if statement"; exit 1; fi
+    # Depends: date 8, echo 8, yell, try
+    
+    local returnState timeCurrent timeNextDay secondsUntilNextDay returnState
+    timeCurrent="$(date --iso-8601=seconds)" ; # Produce `date`-parsable current timestamp with resolution of 1 second.
+    timeNextDay="$(date -d "$timeCurrent next day" --iso-8601=date)"; # Produce timestamp of beginning of tomorrow with resolution of 1 second.
+    secondsUntilNextDay="$(( $(date +%s -d "$timeNextDay") - $(date +%s -d "$timeCurrent") ))" ; # Calculate seconds until closest future midnight (res. 1 second).
+    if [[ "$secondsUntilNextDay" -gt 0 ]]; then
+       returnState="true";
+    elif [[ "$secondsUntilNextDay" -eq 0 ]]; then
+       returnState="warning_zero";
+       yell "WARNING:Reported time until next day exactly zero.";
+    elif [[ "$secondsUntilNextDay" -lt 0 ]]; then
+       returnState="warning_negative";
+       yell "WARNING:Reported time until next day is negative.";
+    fi
+
+    try echo "$secondsUntilNextDay"; # Report
+    
+    # Determine function return code
+    if [[ "$returnState" = "true" ]]; then
+       return 0;
+    elif [[ "$returnState" = "warning_zero" ]]; then
+       return 1;
+    elif [[ "$returnState" = "warning_negative" ]]; then
+       return 2;
+    fi
+} # Report seconds until next day
+timeUntilNextHour(){
+    # Desc: Report seconds until next hour
+    # Version 1.0.1
+    # Output: stdout: integer seconds until next hour
+    # Output: exit code 0 if stdout > 0; 1 if stdout = 0; 2 if stdout < 0
+    # Usage: timeUntilNextHour
+    # Usage: if ! myTTL="$(timeUntilNextHour)"; then yell "ERROR in if statement"; exit 1; fi
+    
+    local returnState timeCurrent timeNextHour secondsUntilNextHour
+    timeCurrent="$(date --iso-8601=seconds)"; # Produce `date`-parsable current timestamp with resolution of 1 second.
+    timeNextHour="$(date -d "$timeCurrent next hour" --iso-8601=hours)"; # Produce `date`-parsable current time stamp with resolution of 1 second.
+    secondsUntilNextHour="$(( $(date +%s -d "$timeNextHour") - $(date +%s -d "$timeCurrent") ))"; # Calculate seconds until next hour (res. 1 second).
+    if [[ "$secondsUntilNextHour" -gt 0 ]]; then
+       returnState="true";
+    elif [[ "$secondsUntilNextHour" -eq 0 ]]; then
+       returnState="warning_zero";
+       yell "WARNING:Reported time until next hour exactly zero.";
+    elif [[ "$secondsUntilNextHour" -lt 0 ]]; then
+       returnState="warning_negative";
+       yell "WARNING:Reported time until next hour is negative.";
+    fi;
+
+    try echo "$secondsUntilNextHour"; # Report
+    
+    # Determine function return code
+    if [[ "$returnState" = "true" ]]; then
+       return 0;
+    elif [[ "$returnState" = "warning_zero" ]]; then
+       return 1;
+    elif [[ "$returnState" = "warning_negative" ]]; then
+       return 2;
+    fi;
+} # Report seconds until next hour